Process of treating precious-metal-bearing materials.



UNITED s ra'rns PATENT orrron.

cHARLEs W MERRILL, or LEAD, SOUTH DAKOTA.

Specification of Letters Patent.

Patented July 17, 1906.

' Application filed October 31, 1905. Serial No. 285.344.

To a, ivhom it nmy concern:

Be it known that 1, CHARLES W. h IERRILL,.

a citizen of the United States, and a resident of Lead, Lawrence county, South Dakota,

have invented a new and useful Improvement in Processes of Treating Precious-Metal- Bearing Materials, of which the following is a specification. j

My invention relates to an improvement in the art of treating precious-metal-bearing materials, particularly those ores or tailings which contain reducing salts or minerals, with cyanogen-bearing solutions.

I have heretofore obtained Letters Patent for improvements in treating that class of ores and tailings which contain reducing salts or minerals with cyanogen-bearing solutions by filling the interstitial space with an oxidizing agent preliminarily to contact with a cyanid solution, and I have heretofore and on or about the 7th day of July, 1905, made application, Serial No. 268,729, for a patent in United States Patent Otfice for a process for treating precious-metal-bearing materials after first contact with a cyanogen-bearing solution by withdrawing the cyanid solution and filling the interstitial space with an oxidizing agent under pressure greater than that of the atmosphere in a closed container and then again subjecting the material to treatment with a cyanogen-bearing solution.

The present application relates to the method of treating such materials after the first contact with a cyano en-bearing solution in any form of container iy means of an oxidizing agent in the form of a solution of an alkali-rnetal or alkaline-earthemetal hypo- -c hlorite, such as hypochlorite of calcium.

As is well known, all methods of crushing ore are divided, generally speaking, into what is known as wet crushing and dry crushin the former necessitatin the presence of iquid in-the material. T e efieot of the liquid being present with the mixed oreis generally incident to the operation and not essentia and hence in the various processes heretofore perfected by me prior to efi'ecting oxidation the liquid is removed from the interstitial spaces of the mass by draining in any convenient manner the containers in which the same is collected, after which the interstitial spaces are filled with the oxidizing agent and the contact thus formed between the finely-divided metal-bearing material and the oxidizing agent is maintained .1 until part or all of tlie reducing -material. has

been'oxidized.

The present invention consists, broadly in using as an oxidizing agent in any form of container, whether open or closed, an alkali hypo'chlorite of calcium. In practice the cyanid solution after the first contact with the precious-metal-bearing material is removed from the interstitial spaces of the crushed ore in the container by draining or otherwise. The solution of hypochlorite, preferably hypochlorite of calcium, which is the form of bleaching-powder in sufficient quantities at low cost, is introduced into the interstitial spaces of the mass in the container, the, effect of which is that such particles of reducing material as may be there present are oxidized. Thereafter hypochlorite solution is displaced, and the particles within the container are subjected to further treatment with the cyanogen-bearing solution. The process can be.conduoted in any form of container to which the hypochlorite solution can be applied after the removal of the cyanogen-bearing solution from the in terstitial spaces of the crushed ore contained to provide an envelop of oxidizing agent around the particles of the crushed ore.

I claim as my invention 1. The improvement in treating a preciousmetal-bearing material with cyanogen-bear.- ing solutionafte'r preliminary contact with such solution, consisting in removing the cyanogen-bearin solutions from the interstitial spaces-of t e crushed material, applying a solution of an alkali-metal or alkaline-earthmetal'hypochlorite to said material and subsequently applying a cyanogen-bearing solution to said material.

2. The improvement in treating aprecious metal-bearing material with cyanogen-bearing solution after preliminary contact with such solution, consisting in removing the cyanogen-bearin tial spaces of t 1e crushed material, applying metal hypochlorite to said material and subor: alkaline-earth metal hypochlorite, such as,

obtainable, mixed with chlorid of calcium insolution from the interstitherein, the eflect of such application being a solution of an alkali-metal or alkaline-earthsequently applying a cyanogembearing solution to said material in one and the same container.

3. The improvement in treating preciousmetal-bearing material containing reducing ing solution to sai agents with cyanogen-hearing solutions consisting in first collecting the crushed material,

same container.

4. The improvement in treating preciousmetal-bearing material containing reducing agents, with cyanogen-bearing solutions, consisting in first collecting the material in a container after preliminary contact with such solutions and after removal of any liquid when there present from the interstitial spaces of the p yi material: in one and thecrushed material, oxidizing all or part of the reducing agent by means of a solution of an alkali-metal or alkaline-earth-metal. hypo- -ch1orite brought into contact with the mate rial in the same container in which the sub- 7 sequent contact with cyanogen-bearing solution is to take place, and subsequent a cyanogen-bearing.solution to said material in saidcontainer.

In testimony that I claim the foregoing as my invention I have signed my name, in presence of two witnesses, this27th dayof Oct0ber,- 1905-.

' CHARLES 'W; MERRILL. Witnesses: I r

A. B, Soo'r'r, AVERILL P. CARTER. 

